In recent years, semiconductor manufacturing technology and compact mounting technology have been rapidly advancing, and reduction in size and weight of various electronic and electric apparatuses has been accordingly remarkable in progress. Such apparatuses include, for example, portable telephones, information terminal apparatuses called PDAs (Personal Digital Assistants), or various computer apparatuses. In addition, reduction in size and weight of portable sound playback apparatuses that play back various types of audio data, and various image-capturing apparatuses as typified by digital video cameras have been remarkably advancing.
Assuming outdoor use as a result of the reduction in size and weight, it is common that the above electronic and electric apparatuses is each provided with a secondary battery used as a power supply. It is required that such a secondary battery have small size and weight, and large capacity. For example, a Li-ion battery, a Ni-MH battery, etc., are used. Also, it is required that the above electronic and electric apparatuses, in particular, notebook personal computers, can be battery-operated for a longer time.
As a sophisticated example, one in which a battery module itself has a built-in control circuit formed by a CPU or the like, as commonly called an intelligent battery, has been proposed. In the intelligent battery, by performing power supply and a charging operation while monitoring states (a battery remaining amount state, a charging/discharging state, etc.) of the secondary battery, accurate remaining-amount calculation and fine power-consumption control can be performed.
In general, in the secondary battery, a phenomenon is found in which it is difficult to continue normal power supply, due to heating of battery cells caused by performing large power discharging when the battery cells deteriorate. Conversely, the above intelligent battery has a mechanism in which, when the temperature of battery cells exceeds a predetermined temperature, power supply from the secondary battery is terminated, thus enabling prevention of abnormal heating of the battery cells which may occur in the conventional secondary battery.
However, there is a problem in that, when the above power-supply termination mechanism operates in an intelligent battery provided in, for example, a computer apparatus, the power supply is suddenly interrupted, thus causing data damage such as loss of the stored content of a memory, and damage to a signal-recorded surface of a hard disk drive.
Also, not only in the computer apparatus, but also in the above mentioned various electronic and electric apparatuses, in many cases, suddenly shutting off power supply may inconvenience a user and may result in serious damage.
Accordingly, the present invention is made in view of the above circumstances of the related art, and an object thereof is to provide a power controller and a power control method in which, in an apparatus operated by power supplied by a secondary battery, the power supply from the secondary battery can be prevented from being suddenly shut off. Also, another object of the present invention is to provide an information processor and a power control program which are able to prevent data damage caused by a sudden shut-off of power supply from the secondary battery.